With respect to a vehicle such as an automobile, a hub bearing for rotatably supporting a wheel is placed in an environment where it is directly exposed to foreign matter such as rainwater, muddy water and dust. Therefore, conventionally, a sealing apparatus for sealing an internal space formed between an outer ring and a hub which are rotatable relatively to each other about an axis is attached to the hub bearing. In this sealing apparatus, a radial lip which is attached to the outer ring and extends to the axis is brought into sliding contact with a hub, and a side lip extending in the axis direction is brought into sliding contact with the hub, thereby sealing lubricant for a rolling element arranged in an inner space of the hub bearing and also preventing foreign matter from intruding into the internal space. Some conventional sealing apparatuses are provided with plural side lips in order to enhance the sealing performance of the internal space to foreign matter (for example, see Japanese Utility Model Registration No. 3201207).